1. Technical Area
This patent relates to a three-dimensional automated warehouse with at least one pair of layered stacked racks, and more particularly to transferring shuttles which are placed on every layer, or on every few layers, of the stack of racks, and which run in a horizontal direction and transfers package(s) to and from the layered stacked racks.
2. Technical Background
A known example of a three dimensional warehouse is described in Japanese Patent Disclosure Heisei 8-324721. The three dimensional warehouse described in this Patent Disclosure is comprised of at least one pair of left and right layered stacks of racks, each containing multiple layers. A transferring shuttle, which can run in a horizontal direction, is implemented for each layer of the stacked racks.
The purpose of the transferring shuttle is to transfer packages in and out of the pair of stacked racks. The shuttles of the prior art are comprised of a running platform which can carry a package on its center and a picking mechanism which loads and unloads the package in the horizontal sideway (left and right) directions perpendicular to the direction that the platform runs.
One such prior art picking mechanism described in the Patent Disclosure Heisei 8-324721, is comprised of a three-stage elastic mechanism placed in front and back of the package carrying area. Each elastic mechanism is of well-known structure, comprised of a fixed rail affixed to the running platform, a first sliding rail which is mounted on the fixed rail so that it can slide, and a second sliding rail which is mounted on the first sliding rail so that it can slide. The first and the second sliding rails are connected by a pulley and belt, so that when the first sliding rail slides on the fixed rail, the second sliding rail slides in the same direction as the first sliding rail. Furthermore, the means of actuation of the first sliding rail is comprised of a motor mounted on the running platform, a pinion mounted on the rotating shaft of the motor, and a rack mounted on the first sliding rail that meshes with the pinion.
On the second sliding rail, there are terminal fingers that operate between the extended position, in which the fingers protrude towards the package carrying area, and the retracted position, in which the fingers are retracted from the package carrying area. By placing the terminal fingers into the extended position so that they can hold the end surfaces of the package, it is possible to load and unload a package.
There is the ever present issue of increasing the storage capacity of a three-dimensional warehouse, and a number of methods have been proposed. One such method is to place packages far back (i.e., away from the running path of the transferring shuttle) on each of the shelves of the stacked racks, for example, in two rows, back and front. To realize this method, the maximum stroke of the elastic mechanism must be doubled.
However, in order to increase the stroke of the elastic mechanism, i.e., to improve the general transferring shuttle such as described in Patent Disclosure Heisei 8-324721, the number of sliding rails must be increased to at least three. Increasing the number of wearable members such as sliding rails may lead to breakage. Also, as the device structure becomes more complex, commonization of purchased parts becomes difficult, and the economy of scale becomes less viable, leading to an increase in manufacturing cost. Furthermore, the increase in the thickness of the elastic mechanism necessitates the designing of sufficient space for the sliding rail above the layered stacked rack and increases the needed clearance between the packages, hindering the increase of the storage capacity in the end.